This repository contains code and documentation for research on non-destructive testing (NDT) of steel–PIR sandwich panels using air-coupled ultrasonic Lamb waves.
The work investigates both a laboratory and an industrial setup for inline defect detection during sandwich panel production. For more information, please read the corresponding paper:
[Insert paper link here]
The corresponding data which can be evaluated with this code is found here:
[Insert data link here]
Lightweight sandwich panels are widely used in industrial construction but may develop air voids or delaminations during production.
This project explores the use of air-coupled ultrasound for detecting such defects non-destructively and inline, eliminating the need for mechanical contact or couplants.
Two systems are implemented:
- 40 kHz Experimental Setup:
Laboratory system using a phased array and laser Doppler vibrometer (LDV) for proof-of-concept measurements. - 216 kHz Industrial Prototype:
Robust, multi-channel system for continuous monitoring during production, using phased air-coupled transducers.
- Phased array beam steering for coupling-angle optimization
- Air-coupled Lamb wave excitation and detection
- Signal processing pipeline: filtering, envelope extraction, spatial filtering
- Defect detection via statistical thresholding
- Inline, multi-channel industrial integration
All file are in the root folder. The data needs to be added to the root folder once cloned.
- Excitation: Air-coupled transducers generate Lamb waves in the steel sheet.
- Acquisition: LDV or air-coupled receiver records surface response.
- Processing: Signals are bandpass-filtered, the envelope is extracted, and amplitudes are spatially filtered.
- Detection: Amplitude deviations exceeding a statistical threshold (e.g., 3σ or 4σ) indicate defects.
- 40 kHz Setup: ~25 % amplitude reduction at defect positions.
- 216 kHz Prototype: 63 % detection rate (no false positives) at 4σ threshold; 90 % detection with 37 % false detections at 3σ threshold.
- Detects both air voids and foam irregularities in production conditions.
If you use this repository in academic work, please cite the corresponding paper
This project is released under the GNU General Public License v3.0. See LICENSE for details.
Christoph Haugwitz